When installing an HRV for indoor air quality, is an independent duct system better than a "simple" installation?
I'm installing an HRV in my new house to improve air quality and mitigate outgassing of pressed wood cabinets, carpet, etc. (Climate zone 5a, so mixed humid conditions; hot summers, chilly winters but not too cold)
Initially, I was going to install a simple exhaust-only system with Panasonic bath fans, but then I came across a study that suggested that exhaust-only systems aren't as helpful for indoor air quality as an ERV (or an HRV):
Ventilation System Effectiveness and Tested Indoor Air Quality Impacts
Building America Report - 1309, March 2013
Armin Rudd and Daniel Bergey
I've attached a plot from that study that shows formaldehyde concentration vs. ventilation type. The ERV gives the best results for formaldehyde reduction, but the air changes per hour for each ventilation type were different (see second attached plot). So it's not exactly a direct comparison even though I think they tried to make the ventilation rates equal in terms of CFM. I was very surprised at the results, but maybe I'm misinterpreting them?
Anyway, in that study, the ERV was ducted independently of the heating and cooling system. I'm wondering if a "simple" installation in which the HRV/ERV is tied into the HVAC return would be significantly different (better or worse) for indoor air quality than an independently ducted HRV? I'm considering both options and only want to pay for independent ducting if it would be better for air quality.
Follow-up question: If I did the "simple" HRV installation I would try to retrofit a Gentech Evergreen IM motor in the air handler. It claims 95 W power usage when run continuously in the fan-on mode. Combined with a good HRV, energy consumption wouldn't be ideal but should be good enough for continuous HRV operation. Does anyone have opinions or experience on doing things this way?
Posted Thu, 07/17/2014 - 16:54
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